I'm really surprised no one mentioned [url= http://www.openfiler.com/%5DOpenFiler%5B/url%5D. Some of us don't have the luxury of shelling out hundreds of thousands or millions of dollars for a solution. Especially if that solution is going to be used in a dev/testing environment.

We have a dev set up with SQL Server on bare metal and VMs. Both instances are using iSCSI targets as local disks and the performance over regular 1Gbps Ethernet is great for our purposes.

OpenFiler also offers paid support if you need a little more assurance and feautres (HA, failover) in the enterprise space. Great tool.